1. Field of the Invention
The present invention relates to an optical print head used as a light source of an exposure system and an image formation apparatus such as a printer, a facsimile apparatus, a copy machine and the like for forming a monochrome image and a color image.
2. Related Background Art
Conventionally, an electrophotographic system is used in a large number of image formation apparatuses such as a printer, a facsimile apparatus, a digital copy machine and the like. That is, the electrophotographic system is a system in which a latent image is formed on an image support body in response to an image signal outputted from an external computer or an image reading device. As an exposure system for this system, an optical print head which is composed by a light source obtained by arraying light emitting elements such as light emitting diodes or the like is often used. As compared with a print head using laser, the optical print head is compact in size. Thus, it is possible to easily constitute a silent image formation apparatus.
The light emitting elements in this optical print head are composed of light emitting diodes or the like. Since the element irradiates spread light from a certain point or surface, the spread light irradiated from the light emitting element has to be formed as a focused image on each microscopic spot in order to form the latent image on the image support body. For this reason, the optical print head is frequently provided with an image-formation element array represented by a rod lens array.
However, a number of the image-formation element arrays merely condense a part of the light spread from the light emitting element. Therefore, the exposed light quantity becomes considerably small as compared with the entire light quantity spread from the light emitting elements.
On the other hand, a high-speed image formation apparatus has been recently required. In a case where image formation is performed at high speed, since an exposure time of the light irradiated from the light emitting element becomes short, there is some fear that the sufficient exposure light quantity cannot be rendered and thus a successful latent image cannot be obtained.